A new proprioceptive approach to the treatment of scoliosis is proposed. This new approach requires a portable three-dimensional measurement system to detect the postural changes of a scoliotic trunk. Seven topographical features that significantly contributed to trunk deformities were identified. An objective method was developed examining trunk deformity. This objective method showed that the seven topographical features could be reliably and repeatably measured. Also, this method was chosen to assess the treatment outcome. To monitor the postural changes of a scoliotic trunk during daily activities, an electromagnetic three-dimensional measurement system has been investigated. An algorithm based on the electromagnetic theory was developed and implemented into the measurement system so that automatic measurements were obtained. Error analysis was done to demonstrate the accuracy of the system. Hardware and software challenges on investigating the electromagnetic approach were solved by theoretical analysis and laboratory testing. Finally a novel design of a three-dimensional low-power portable electromagnetic measurement system was developed. Experimental tests and clinical trials were done to verify that the accuracy of the system was able to detect the postural changes of human trunks.